Information security is becoming a crucial issue as more and more information are collected, accessed, and analyzed. The ever-increasing popularity and potential of Cloud Computing takes the information security issue to the center stage of the computing world. Conventional information security measures mainly rely on the access control to the information. That is, different levels of authorities are assigned to the users and the information that the users are authorized to access. This type of security measures suffers several disadvantages. First, the access control mechanism only determines what information a user can access and takes no notice of the method, frequency, or timing the user accesses the information. Second, the access control mechanism focuses on the activity of an individual member and again takes no notice on aggregated access of a group of members. The aforementioned disadvantages identify the possible security loopholes caused by the failure to notice a sudden change in behavior of a member or a group of members, which accounts for a majority of information security breaches in recent years. In other words, the conventional access control mechanism cannot effectively prevent the leakage of information caused by insiders. Hence, it is imperative to devise a method that profiles the individual and collective behaviors of a plurality of members in a network data environment.